The present invention relates to a belt tensioner which restrains a belt of an engine from loosening and a belt exchanging method of the same.
An engine is equipped with auxiliary components, such as an alternator, a water pump, a compressor of air conditioner. There are provided some axes which extend from the components in parallel to a crankshaft, and pulleys are attached to one ends of the axes. A belt is disposed between each of the pulleys and the crankshaft so that the axes of the components can be rotated (driven) by the crankshaft.
There occurs looseness at the belt on a looseness side while the belt rotates. Accordingly, a belt tensioner is generally provided to restrain this looseness. For example, the belt tensioner comprises a bearing member (fixation member) attached to an end face of an engine body, a tensioner arm, a base end portion of which is supported rotatably at the bearing member via an axis in parallel to an engine output shaft, a pulley supported rotatably at a free end portion of the tensioner arm via an axis in parallel to the engine output shaft, and a biasing mechanism provided between the bearing member and the tensioner arm so as to bias the tensioner arm toward the belt.
In the above-described belt tensioner, it may be required that the pulley of the tensioner belt is provided so as to retreat in a counter biasing direction in order to dispose the belt between the pulleys. Japanese Patent Laid-Open Publication No. 09-177911 discloses a device which may improve a belt attachment work in a vehicle assembling, in which small holes are formed at the bearing member and the tensioner arm respectively, and a stopper pin is inserted into these small holes in a direction in parallel to the above-described axes, thereby keeping the tensioner arm in a position where the tensioner arm retreats toward the counter biasing direction.
Further, Japanese Patent Laid-Open Publication No. 2006-250286 discloses a device in which at a specified face of the tensioner arm on an counter engine-body side are provided plural projections with which a lever-shaped jig engages, and by rotating the lever-shaped jig engaging with the projections in a counter biasing direction, the tensioner arm may be provided so as to retreat toward the counter biasing direction.
According to the device of the former of the above-described patent publications, since many devices and the like are disposed in front of the engine's end face in the assembled vehicle, it may be difficult that the stopper pin is inserted into the above-described holes after the vehicle has been assembled. This is because the stopper pin being inserted might interfere with the above-described devices and the like. Accordingly, it may be required that such devices and the like are detached or the engine itself is disassembled when the belt exchanging is conducted at a regular maintenance or the like. Thus, the belt changing would be troublesome.
According to the device of the latter of the above-described patent publications, since there is provided no mechanism for holding the belt tensioner which has been rotated by the belt exchanging jig, two workers may be necessary for operating the belt exchanging jig and exchanges the belt. Thus, the belt exchanging would not be conducted by a single worker.